body{
    background-image: url(../images/bj.jpg);
    background-repeat: no-repeat;
    /* background-size: contain;*/
    background-size: cover;
}

.container{
    width: 985px;
    height: 552px;
    margin: 100px auto;
    position: relative;
}

.row{
    display: flex;
    justify-content: space-between;
}

.item{
    opacity: 0.5;
}

.active{
    opacity: 1;
}

.btn{
    background-image: url(../images/btn.jpg);
    background-repeat: no-repeat;
    width: 150px;
    height: 68px;
    color: #fff;
    line-height: 68px;
    text-align: center;
    cursor: pointer;
    font-size: 20px;
    position: absolute;
    left: 50%;
    top: 70%;
    transform: translate(-50%,-50%);
    border-radius: 10px;
}